Nowadays, audio and video products are gradually used in homes. Consequently, the market demands on sound playing devices (e.g. single speakers or stereo devices) are growing. For maintaining the quality of the sound playing devices, after the sound playing devices are produced at the production side, it is necessary to test the sound playing devices. After the testing procedure is done, the manufacturer may assure that no buzz is generated while the sound playing devices play sound.
In accordance with a conventional testing method, after the signals with different frequencies are continuously transmitted to the sound playing device, the tester judges whether the sound outputted from the sound playing device contains a buzz by manually hearing the signals with ears. Consequently, the quality of the sound playing device may be discriminated.
However, the testing procedure has to be implemented by the trained testers. Since the experiences and the body conditions of different testers are distinguished, the judgment about the testing result is very subjective and lacks of consistence. Moreover, after the hearing system of the tester has been intensively stimulated for a long time, the hearing system is possibly hurt.
For overcoming the above drawbacks and increasing the testing efficiency, there is a need of providing an automatic testing method and an automatic testing system to use an instrument to perform the testing procedure in replace of the human hearing system.